THE NUMBERS, EXPLAINED
How to use this calculator.
One rectangular roof slope. Alternate courses begin with a half-width shingle; a course consumes the required full stock pieces even if edges are trimmed. No reuse of offcuts.
Start with your inputs
Enter miniature roof slope width (mm), roof slope length (mm), shingle width (mm), exposed height per course (mm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Miniature roof slope width (mm) | 100 |
| Roof slope length (mm) | 80 |
| Shingle width (mm) | 20 |
| Exposed height per course (mm) | 20 |
A worked example
With the example inputs above, course count is 4. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Course count | 4 |
| Stock shingles required | 22 |
| Alternate course offset (mm) | 10 |
How this is calculated
Course count
Round slope length divided by exposed course height upward.
Stock shingles required
Add full and half-offset row requirements.
Alternate course offset (mm)
Start every second course half a shingle left of the edge.
Symbols and units
- a
- Miniature roof slope width (mm)
- b
- Roof slope length (mm)
- c
- Shingle width (mm)
- d
- Exposed height per course (mm)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
One rectangular roof slope. Alternate courses begin with a half-width shingle; a course consumes the required full stock pieces even if edges are trimmed. No reuse of offcuts.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Course count; Stock shingles required; Alternate course offset (mm). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: One rectangular roof slope. Alternate courses begin with a half-width shingle; a course consumes the required full stock pieces even if edges are trimmed. No reuse of offcuts.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
OpenStax Prealgebra 2e — arithmetic and proportions ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
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